Component of work machine, work machine, and method for manufacturing component of work machine

Abstract

This component of a work machine has a box-shaped structure (BX1). The box-shaped structure (BX1) is constituted by a plurality of plate members (SP1, SP2, TP1, BP1). The box-shaped structure (BX1) has a first corner region (56) and a second corner region (57) at an upper corner part (51) that extends from a first end (61) toward a second end (62) of the box-shaped structure (BX1). The second corner region (57) is provided between the first corner region (56) and the second end (62). The first corner region (56) is constituted by a joint structure in which two or more plate members among the plurality of plate members (SP1, SP2, TP1, BP1) are joined. The second corner region (57) is constituted by a bent structure in which one plate member among the plurality of plate members (SP1, SP2, TP1, BP1) is bent.

Description

Component of working machine, working machine, and method for manufacturing component of working machine

[0001] The present disclosure relates to a component of a working machine, a working machine, and a method for manufacturing a component of a working machine.

[0002] Conventionally, a box-shaped boom is disclosed, for example, in Japanese Utility Model Laid-Open No. 54-158408 (Patent Document 1). Patent Document 1 discloses a boom formed by welding and joining two press-formed boom members.

[0003] Japanese Utility Model Laid-Open No. 54-158408

[0004] In the boom member described in Patent Document 1, the processing accuracy of press molding decreases. Accordingly, productivity decreases.

[0005] The present disclosure has been made in view of the above, and an object thereof is to provide a component of a working machine, a working machine, and a method for manufacturing a component of a working machine that can improve productivity.

[0006] The component of a working machine according to the present disclosure includes a box-shaped structure. The box-shaped structure is constituted by a plurality of plate materials. The box-shaped structure has a first corner region and a second corner region at a corner portion extending from a first end toward a second end of the box-shaped structure. The second corner region is provided between the first corner region and the second end. The first corner region is constituted by a joining structure in which two or more plate materials among the plurality of plate materials are joined to each other. The second corner region is constituted by a bent structure in which one plate material among the plurality of plate materials is bent.

[0007] The working machine according to the present disclosure includes a working machine and a main body that supports the working machine. The working machine includes the component of the working machine described above.

[0008] The manufacturing method disclosed herein is a method for manufacturing components of a work machine. The components of the work machine have a box-shaped structure. The box-shaped structure is composed of a plurality of plate materials. The box-shaped structure has a first corner region and a second corner region at the corner extending from the first end to the second end of the box-shaped structure. The second corner region is provided between the first corner region and the second end. The manufacturing method comprises the following steps: Forming at least a part of the first corner region by joining two or more plate materials from the plurality of plate materials. Forming the second corner region by bending one of the plurality of plate materials.

[0009] According to this disclosure, it is possible to provide components for work machines that can improve productivity, work machines, and methods for manufacturing components for work machines.

[0010] This is a schematic perspective view showing the configuration of a work machine in one embodiment of the present disclosure. This is a side view showing the configuration of the boom in the work machine shown in Figure 1. This is a perspective view showing the configuration of the boom in the work machine shown in Figure 1. This is a cross-sectional view corresponding to the line IV-IV in Figure 2. This is a cross-sectional view corresponding to the line V-V in Figure 2. This is an enlarged cross-sectional view showing the configuration of a corner formed by a joint structure. This is a diagram showing the configuration of a modified boom 1, and is a cross-sectional view corresponding to the line V-V in Figure 2. This is a diagram showing the configuration of a modified boom 2, and is a cross-sectional view corresponding to the line V-V in Figure 2. This is a side view showing the configuration of the arm in the work machine shown in Figure 1. This is a perspective view showing the configuration of the arm in the work machine shown in Figure 1. This is a cross-sectional view corresponding to the line XI-XI in Figure 9. This is a cross-sectional view corresponding to the line XII-XII in Figure 9. This is a flowchart schematicly showing a method for manufacturing a boom in one embodiment of the present disclosure. This is a schematic diagram illustrating the process of joining the side plate, bottom plate, and boss member in the method for manufacturing a boom. This is a schematic diagram illustrating the process of joining the side plate, bottom plate, and boss member, joining the internal rib, and joining the top plate in the method for manufacturing a boom. This is a flowchart schematicly showing a modified version of the method for manufacturing a boom. This is a schematic diagram illustrating the process of forming the first and second box sections, and the process of joining the first and second box sections. This is a schematic diagram illustrating the process of joining the side plate, top plate, and boss member, and the process of joining the internal ribs, in the manufacturing method of the arm. This is a schematic diagram illustrating the process of joining the bottom plate, in the manufacturing method of the arm.

[0011] The embodiments of this disclosure will be described below with reference to the drawings. In the specification and drawings, the same components or corresponding components are denoted by the same reference numerals, and redundant descriptions are avoided. In addition, for the sake of clarity, some components may be omitted or simplified in the drawings.

[0012] In the following explanation, "up," "down," "forward," "backward," "left," and "right" refer to directions relative to the operator seated in the driver's seat 4S within the driver's cab 4 shown in Figure 1. Also, in Figures 2, 4, 5, 7, 8, 9, 11, and 12, the forward / backward direction is indicated by X, the left / right direction by Y, and the up / down direction by Z.

[0013] <Configuration of the Working Machine> As an example of the working machine of this disclosure, the configuration of a hydraulic excavator will be explained with reference to Figure 1.

[0014] Figure 1 is a schematic perspective view showing the configuration of a work machine in one embodiment of the present disclosure. As shown in Figure 1, the hydraulic excavator 100 has a main body 1 and a work machine 2 that is operated by hydraulics. The main body 1 has a slewing body 3 and a traveling body 5. The traveling body 5 has a pair of tracks 5Cr and a traveling motor 5M. The hydraulic excavator 100 can move by the rotation of the tracks 5Cr. The traveling motor 5M is provided as a drive source for the traveling body 5. The traveling motor 5M is a hydraulic motor that is operated by hydraulics. The traveling body 5 may also have wheels (tires).

[0015] The slewing body 3 is positioned on and supported by the traveling body 5. The slewing body 3 is capable of rotating relative to the traveling body 5 around its pivot axis RX. The slewing body 3 has a cab 4. Inside the cab 4 is a driver's seat 4S where the operator sits. The operator (crew) can sit in the cab 4 and operate the work equipment 2, rotate the slewing body 3 relative to the traveling body 5, and operate the hydraulic excavator 100 using the traveling body 5.

[0016] The work machine 2 is supported by the slewing body 3. The work machine 2 has a boom 6, an arm 7, and a bucket 8. The work machine 2 further has a boom cylinder 10, an arm cylinder 11, and a bucket cylinder 12.

[0017] The boom 6 is rotatably connected to the main body 1 (the traveling body 5 and the slewing body 3). Specifically, the base end of the boom 6 is rotatably connected to the slewing body 3 with the boom foot pin 13 as the pivot point.

[0018] The arm 7 is rotatably connected to the boom 6. Specifically, the base end of the arm 7 is rotatably connected to the tip of the boom 6 with the boom top pin 14 as the pivot point. The bucket 8 is rotatably connected to the arm 7. Specifically, the base end of the bucket 8 is rotatably connected to the tip of the arm 7 with the arm top pin 15 as the pivot point.

[0019] One end of the boom cylinder 10 is connected to the slewing body 3, and the other end is connected to the boom 6. The boom 6 can be driven relative to the main body 1 by the boom cylinder 10. This drive allows the boom 6 to rotate vertically relative to the slewing body 3, with the boom foot pin 13 as the pivot point.

[0020] One end of the arm cylinder 11 is connected to the boom 6, and the other end is connected to the arm 7. The arm 7 is driveable relative to the boom 6 by the arm cylinder 11. This drive allows the arm 7 to rotate vertically or longitudinally relative to the boom 6, with the boom top pin 14 as the pivot point.

[0021] One end of the bucket cylinder 12 is connected to the arm 7, and the other end is connected to the bucket link 17. The bucket link 17 is supported by the arm 7 via a link pin 16. The bucket 8 is driveable relative to the arm 7 by the bucket cylinder 12. This drive allows the bucket 8 to rotate vertically relative to the arm 7 with the arm top pin 15 as the pivot point. The boom cylinder 10, arm cylinder 11, and bucket cylinder 12 are all hydraulic cylinders.

[0022] <Boom Configuration> Next, the boom configuration of this embodiment will be explained using Figures 2 to 5.

[0023] Figures 2 and 3 are side and perspective views, respectively, showing the configuration of the boom in the work machine shown in Figure 1. Figure 4 is a cross-sectional view corresponding to the line IV-IV in Figure 2. Figure 5 is a cross-sectional view corresponding to the line V-V in Figure 2.

[0024] As shown in Figures 2 and 3, the boom 6 has a box-shaped structure BX1, a boom top 6a, and a boom foot 6b. The box-shaped structure BX1 has a first end 61 and a second end 62. The first end 61 is the tip end of the boom 6 and faces the arm 7 (Figure 1). The second end 62 is the base end of the boom 6 and faces the main body 1 (Figure 1).

[0025] The box-shaped structure BX1 extends from the first end 61 to the second end 62. In a side view, the box-shaped structure BX1 is bent in an upward convex shape. A side view refers to the viewpoint from the left-right direction Y, relative to the operator seated in the driver's seat 4S (Figure 1).

[0026] The boom top 6a and boom foot 6b are each cast, for example, by casting. The boom top 6a is the portion into which the boom top pin 14 (Figure 1) is inserted. The boom top 6a is joined to the first end 61, for example, by welding. The boom foot 6b is the portion into which the boom foot pin 13 (Figure 1) is inserted. The boom foot 6b is joined to the second end 62, for example, by welding.

[0027] The box-shaped structure BX1 has a hollow, box-like shape inside. The box-shaped structure BX1 is composed of multiple plate materials. The multiple plate materials include an upper plate TP1, a pair of side plates SP1 and SP2, and a lower plate BP1. Each of the upper plate TP1, the pair of side plates SP1 and SP2, and the lower plate BP1 is made of, for example, steel.

[0028] As shown in Figure 2, with the first end 61 and second end 62 of the box-shaped structure BX1 positioned in the front and rear directions X respectively, the upper plate TP1 is positioned above the lower plate BP1. The upper plate TP1 and the lower plate BP1 face each other with a gap in the vertical direction Z. In a side view, the lower plate BP1 is bent so as to be convex upwards.

[0029] As shown in Figure 3, the pair of side plates SP1 and SP2 are joined to each other, for example, by welding. Therefore, a weld line WL1 formed by welding is provided between the pair of side plates SP1 and SP2. The upper ends of each of the pair of side plates SP1 and SP2 are joined to the upper plate TP1, for example, by welding. The lower ends of each of the pair of side plates SP1 and SP2 are joined to the lower plate BP1, for example, by welding.

[0030] The first end 61 is composed of an upper plate TP1, a pair of side plates SP1 and SP2, and a lower plate BP2. The second end 62 is composed of a pair of side plates SP1 and SP2, and a lower plate BP2. The upper plate TP1 is separated from the second end 62.

[0031] The box-shaped structure BX1 has upper corners 51 and 52. Each of the upper corners 51 and 52 corresponds to an example of a "corner" in this disclosure. Upper corner 51 is the upper left corner of the box-shaped structure BX1, and upper corner 52 is the upper right corner of the box-shaped structure BX1. Each of the upper corners 51 and 52 extends from a first end 61 toward a second end 62 and reaches the second end 62.

[0032] The box-shaped structure BX1 has a first corner region 56 and a second corner region 57 at its upper corner 51. The first corner region 56 reaches the first end 61. The second corner region 57 reaches the second end 62. The second corner region 57 is located between the first corner region 56 and the second end 62. The second corner region 57 extends in a straight line.

[0033] The configuration of the upper corner portion 52 is the same as that of the upper corner portion 51. Specifically, the box-shaped structure BX1 has a third corner region 58 and a fourth corner region 59 at the upper corner portion 52. The third corner region 58 reaches the first end 61. The fourth corner region 59 reaches the second end 62. The fourth corner region 59 is provided between the third corner region 58 and the second end 62. The fourth corner region 59 extends in a straight line.

[0034] As shown in Figures 4 and 5, the box-shaped structure BX1 has a box shape with a rectangular cross-section (a plane cut in the vertical direction Z). The box-shaped structure BX1 has an internal space IP1 surrounded by an upper plate TP1, a pair of side plates SP1 and SP2, and a lower plate BP1. The internal space IP1 is hollow.

[0035] As shown in Figure 4, the first corner region 56 is composed of a joint structure in which the upper plate TP1 and the side plate SP1 are joined. Therefore, the first corner region 56 is composed of a joint structure in which two or more plates from among the multiple plates that make up the box-shaped structure BX1 are joined together. In the first corner region 56, the upper plate TP1 and the side plate SP1 are joined, for example, by welding. Therefore, an upper welded portion W1 formed by welding is provided in the first corner region 56.

[0036] The third corner region 58 is formed by a joint structure in which the upper plate TP1 and the side plate SP2 are joined. Therefore, the third corner region 58 is formed by a joint structure in which two or more plates from among the multiple plates constituting the box-shaped structure BX1 are joined. In the third corner region 58, the upper plate TP1 and the side plate SP2 are joined, for example, by welding. Therefore, an upper welded portion W2 formed by welding is provided in the third corner region 58.

[0037] As shown in Figure 5, the second corner region 57 is formed by a bent structure in which the side plate SP1 is folded. Therefore, the second corner region 57 is formed by a bent structure in which one of the multiple plate materials constituting the box-shaped structure BX1 is folded. The fourth corner region 59 is formed by a bent structure in which the side plate SP2 is folded. Therefore, the fourth corner region 59 is formed by a bent structure in which one of the multiple plate materials constituting the box-shaped structure BX1 is folded.

[0038] Each of the second and fourth angular regions 57 and 59 is composed in cross-sectional shape of, for example, two curved sections and a flat section connecting the two curved sections. Each of the second and fourth angular regions 57 and 59 is a bent structure formed in cross-sectional shape of, for example, two 45° bends.

[0039] As shown in Figures 4 and 5, the box-shaped structure BX1 has lower corners 53 and 54. Lower corner 53 is the lower left corner of the box-shaped structure BX1, and lower corner 54 is the lower right corner of the box-shaped structure BX1.

[0040] The lower corner portion 53 is constructed by a joint structure in which the side plate SP1 and the lower plate BP1 are joined. In the lower corner portion 53, the side plate SP1 and the lower plate BP1 are joined, for example, by welding. Therefore, a lower welded portion W3 formed by welding is provided in the lower corner portion 53. Similarly, the lower corner portion 54 is constructed by a joint structure in which the side plate SP2 and the lower plate BP1 are joined. In the lower corner portion 54, the side plate SP2 and the lower plate BP1 are joined, for example, by welding. Therefore, a lower welded portion W4 formed by welding is provided in the lower corner portion 54.

[0041] As shown in Figure 2, the upper plate TP1 has a flat portion FP1 and a curved portion RP1. The flat portion FP1 constitutes the first end E1 of the upper plate TP1. The first end E1 is located at the first end 61. The curved portion RP1 is located closer to the second end 62 than the flat portion FP1. The curved portion RP1 constitutes the second end E2 of the upper plate TP1. Therefore, the second end E2 is located closer to the second end 62 than the first end E1.

[0042] The flat plate portion FP1 extends linearly from the first end E1 toward the curved portion RP1. The flat plate portion FP1 has a surface OF1 and a back surface IF1. Surface OF1 constitutes a part of the outer surface of the box-shaped structure BX1. Back surface IF1 is opposite to surface OF1. Back surface IF1 faces the internal space IP1 (Figure 4) of the box-shaped structure BX1.

[0043] The curved portion RP1 is connected to the flat portion FP1. The curved portion RP1 curves upward (in the direction from the back surface IF1 to the front surface OF1). Specifically, the curved portion RP1 curves upward from the boundary between the flat portion FP1 and the curved portion RP1 to an intermediate point towards the second end E2, and then extends in a straight line from that intermediate point to the second end E2.

[0044] The second corner region 57 is joined to the curved portion RP1. The second corner region 57 extends along the thickness direction of the curved portion RP1 (direction of arrow T in Figure 2). Note that the thickness direction refers to the thickness direction of the portion of the curved portion RP1 to which the second corner region 57 is joined.

[0045] As shown in FIG. 3, the fourth corner region 59 is joined to the warped raised portion RP1. The fourth corner region 59 extends along the thickness direction of the warped raised portion RP1. Each of the second corner region 57 and the fourth corner region 59 is joined to a linearly extending portion of the warped raised portion RP1.

[0046] As shown in FIG. 2, the upper plate TP1 includes a first plate member 41 and a second plate member 42. The first plate member 41 is flat-shaped. One end of the first plate member 41 is located at the first end 61. The first plate member 41 constitutes a part of the flat plate portion FP1 and the first end portion E1. The first plate member 41 faces the arm cylinder 11 (FIG. 1). The arm cylinder 11 corresponds to an example of the "hydraulic cylinder" in the present disclosure.

[0047] The second plate member 42 is continuous with the first plate member 41. Specifically, the second plate member 42 is joined to the other end of the first plate member 41 by, for example, welding. Note that the first plate member 41 and the second plate member 42 may be formed of a single plate material. The second plate member 42 constitutes a part of the flat plate portion FP1, the warped raised portion RP1, and the second end portion E2.

[0048] The second corner region 57 is joined to the second plate member 42. Specifically, the end of the second corner region 57 opposite to the end located at the second end 62 is joined to the second plate member 42 by, for example, welding. The upper welded portion W1 (FIG. 4) provided in the first corner region 56 reaches the end of the second corner region 57 joined to the second plate member 42.

[0049] As shown in FIG. 3, the fourth corner region 59 is joined to the second plate member 42. Specifically, the end of the fourth corner region 59 opposite to the end located at the second end 62 is joined to the second plate member 42 by, for example, welding. The upper welded portion W2 (FIG. 4) provided in the third corner region 58 reaches the end of the fourth corner region 59 joined to the second plate member 42.

[0050] The portions of the side plates SP1 and SP2 located between the second corner region 57 and the fourth corner region 59 are referred to as the upper surface portion 40. A weld line WL1 is provided on the upper surface portion 40, for example. One end of the upper surface portion 40 is located at the second end 62. The other end of the upper surface portion 40 is joined to the second plate material 42 by welding, for example. Therefore, the upper weld portion W1 (Figure 4) and the upper weld portion W2 (Figure 4) are connected between the other end of the upper surface portion 40 and the second plate material 42.

[0051] As shown in Figure 2, in a side view, the imaginary straight line 99 that overlaps the outer surface (surface OF1) of the first plate material 41 intersects the second corner region 57. Part of the second corner region 57 and the second end E2 are located above the imaginary straight line 99. The second corner region 57 is inclined with respect to the imaginary straight line 99. Specifically, the second corner region 57 is inclined downwards (in the direction from the surface OF1 to the back surface IF1) as it moves away from the first plate material 41.

[0052] Although not shown in the diagram, in a side view, the virtual line 99 intersects with the fourth corner region 59. The fourth corner region 59 is located above the virtual line 99. The fourth corner region 59 is inclined with respect to the virtual line 99. Specifically, the fourth corner region 59 is inclined downwards as it moves away from the first plate material 41.

[0053] As shown in Figure 3, the side plate SP1 has, for example, a third plate material 43 and a fourth plate material 44. One end of the third plate material 43 is located at the first end 61. The third plate material 43 constitutes at least a part of the first corner region 56. The third plate material 43 is joined to the upper plate TP1 and the lower plate BP1, respectively, by welding, for example.

[0054] One end of the fourth plate 44 is located at the second end 62. The other end of the fourth plate 44 is joined to the other end of the third plate 43, for example, by welding. The fourth plate 44 is joined to the upper plate TP1, the lower plate BP1, and the side plate SP2, for example, by welding. The fourth plate 44 constitutes part of the first corner region 56 and the second corner region 57. The third plate 43 is thinner than the fourth plate 44.

[0055] Although not shown in the diagram, the side plate SP2, like the side plate SP1, has, for example, a fifth plate and a sixth plate. The fifth plate and the sixth plate correspond to the third plate 43 and the fourth plate 44, respectively. One end of the fifth plate is located at the first end 61. The fifth plate constitutes at least a part of the third corner region 58. The fifth plate is joined to the upper plate TP1 and the lower plate BP1, respectively, by welding, for example.

[0056] One end of the sixth plate is located at the second end 62. The other end of the sixth plate is joined to the other end of the fifth plate, for example, by welding. The sixth plate is joined to the upper plate TP1, the lower plate BP1, and the fourth plate 44, for example, by welding. The sixth plate constitutes part of the first corner region 56 and the second corner region 57. The fifth plate is thinner than the sixth plate.

[0057] As shown in Figure 3, the weld line WL1 between side plate SP1 and side plate SP2 is provided between the second corner region 57 and the fourth corner region 59. Side plate SP2 may be mirror symmetric to side plate SP1 with respect to a plane that includes the weld line WL1 and extends in the vertical direction Z and the front-rear direction X. As shown in Figure 5, side plates SP1 and SP2 and backing plate P1 may be joined by the weld line WL1.

[0058] As shown in Figures 2 and 3, the boom 6 has a first arm cylinder bracket 6c and a center boss 6d. The first arm cylinder bracket 6c corresponds to an example of a "cylinder bracket" of this disclosure. The first arm cylinder bracket 6c is a portion that rotatably supports one end of the arm cylinder 11 (Figure 1). The arm cylinder 11 is arranged to extend along the direction toward the first end 61 from the first arm cylinder bracket 6c. The first arm cylinder bracket 6c is joined to the second plate material 42 of the upper plate TP1. The first arm cylinder bracket 6c protrudes upward from the upper plate TP1.

[0059] The second corner region 57 is provided between the first arm cylinder bracket 6c and the second end 62. Specifically, the second corner region 57 is provided between the portion of the second plate material 42 to which the first arm cylinder bracket 6c is joined and the second end 62.

[0060] The center boss 6d is the part that rotatably supports the other end of the boom cylinder 10 (Figure 1). The center boss 6d is provided so as to penetrate each of the pair of side plates SP1 and SP2. The center boss 6d is joined to each of the pair of side plates SP1 and SP2. The center boss 6d, boom foot 6b, and boom top 6a are also referred to as boss members.

[0061] As shown in Figure 2, the box-shaped structure BX1 has, for example, internal ribs 49. The internal ribs 49 are located within the internal space IP1 (Figure 4) of the box-shaped structure BX1. The lower end of the internal ribs 49 is joined to the lower plate BP1. The upper end of the internal ribs 49 is joined to the center boss 6d. Note that the box-shaped structure BX1 does not necessarily have internal ribs 49.

[0062] <Effects> Next, the effects of the boom 6 according to this embodiment will be explained.

[0063] When forming the components of boom 6, the sheet metal is sometimes bent. If the length of the bent portion is excessively long, the processing accuracy decreases. This can lead to defects such as misalignment of the weld position when welding the bent parts. As a result, productivity decreases.

[0064] According to this embodiment, the upper corner portion 51 of the box-shaped structure BX1 has a first corner region 56 and a second corner region 57. The first corner region 56 is composed of a joint structure in which the upper plate TP1 and the side plate SP1 are joined. The second corner region 57 is composed of a bent structure in which the side plate SP1 is folded. Therefore, bending is performed only on a part of the upper corner portion 51. Consequently, the accuracy of the bending is improved compared to the case in which bending is performed on the entire upper corner portion 51. This suppresses the occurrence of defects such as misalignment of the welding position. As a result, productivity is improved.

[0065] Figure 6 is an enlarged cross-sectional view showing the structure of a corner formed by a joint structure. As shown in Figure 6, when a corner is formed by welding two plate materials together, for example, a residual root portion R is formed at the corner that is not joined by the weld W. When torsional moment and bending moment are applied to the corner, cracks may occur starting from the residual root portion R.

[0066] In this embodiment, the first arm cylinder bracket 6c is joined to the upper plate TP1. The second corner region 57 is provided between the first arm cylinder bracket 6c and the second end 62 of the box-shaped structure BX1. Therefore, the second corner region 57 is located at a position where the force applied from the arm cylinder 11 to the box-shaped structure BX1 via the first arm cylinder bracket 6c is relatively concentrated. Because the second corner region 57 located at this position is constructed with a bending structure, the occurrence of cracks in the box-shaped structure BX1 is suppressed.

[0067] According to this embodiment, the upper plate TP1 is flat and has a first plate material 41 facing the arm cylinder 11. In a side view, a virtual straight line 99 that overlaps the outer surface (surface OF1) of the first plate material 41 intersects the second corner region 57. Therefore, compared to the case where the second corner region 57 does not intersect the virtual straight line 99 (i.e., when the entire second corner region 57 is located below the virtual straight line 99), the cross-sectional area of ​​the box-shaped structure BX1 in the vertical section is increased. This improves the strength of the boom 6.

[0068] According to this embodiment, the upward-curving portion RP1 of the upper plate TP1 is curved upward from the back surface IF1 toward the front surface OF1. The second corner region 57 is joined to the upward-curving portion RP1 and extends along the thickness direction of the upward-curving portion RP1. Therefore, when welding the upper plate TP1 and the side plate SP1, fillet welding can be performed with the upward-curving portion RP1 and the second corner region 57 forming approximately a 90° angle. Consequently, fillet welding of the upward-curving portion RP1 and the second corner region 57 can be performed continuously with the fillet welding of the portion of the side plate SP1 other than the second corner region 57 and the upper plate TP1. As a result, a smoothly connected upper weld portion W1 is formed when joining the upper plate TP1 and the side plate SP1. Consequently, the occurrence of cracks originating from the upper weld portion W1 is suppressed.

[0069] Bending a corner formed by a bent structure to curve it is a difficult process. In this embodiment, the second corner region 57 extends along the thickness direction of the curved portion RP1. Therefore, bending the second corner region 57 is unnecessary during the manufacturing process of the boom 6. This improves productivity.

[0070] According to this embodiment, the side plate SP1 has a third plate material 43 that constitutes at least a part of the first corner region 56 and a fourth plate material 44 that constitutes the second corner region 57. The third plate material 43 is thinner than the fourth plate material 44. Therefore, it is possible to improve the strength of the second corner region 57, where relatively high strength is required, while suppressing an increase in the overall weight of the boom 6.

[0071] <Modified Boom 1> Next, the configuration of Modified Boom 6 1 will be explained using Figure 7.

[0072] Figure 7 is a diagram showing the configuration of a modified example 1 of the boom 6, and is a cross-sectional view corresponding to the line V-V in Figure 2. As shown in Figure 7, each of the second corner region 57 and the fourth corner region 59 may be composed of a single curved portion in its cross-sectional shape. Each of the second corner region 57 and the fourth corner region 59 may be a bent structure formed by a 90° bend in its cross-sectional shape.

[0073] Each of the second and fourth corner regions 57 and 59 may have a cross-sectional shape that, for example, is a curved shape with a single radius of curvature overall, or it may consist of a combination of curved shapes with multiple radii of curvature. If each of the second and fourth corner regions 57 and 59 has a cross-sectional shape that, for example, is a curved shape with a single radius of curvature overall, it may have a curved shape that bulges outward from the internal space IP1 of the box-shaped structure BX1.

[0074] <Modified Boom 2> Next, the configuration of modified boom 6 2 will be explained using Figure 8.

[0075] Figure 8 is a diagram showing the configuration of a modified example 2 of the boom 6, and is a cross-sectional view corresponding to the line V-V in Figure 2. As shown in Figure 8, the second corner region 57 and the fourth corner region 59 may be made of a single plate. The box-shaped structure BX1 does not have to have a weld line WL1 (Figure 3). For this reason, the fourth plate 44 (Figure 2) and the sixth plate may be made of a single plate. Furthermore, the third plate 43, the fourth plate 44, the fifth plate, and the sixth plate may be made of a single plate.

[0076] <Arm Configuration> In the above embodiment, the configuration of the boom 6 of the work machine 2 was described. The present invention is also applicable to the arm 7 of the work machine 2. The components of the work machine that are the subject of the present invention refer to either the boom 6 or the arm 7. The configuration of the arm 7 of this embodiment will be described below with reference to Figures 9 to 12. Note that the explanation will focus on the differences from the configuration of the boom 6 described above, and the explanation of points that are the same as the configuration of the boom 6 will be omitted. Among the components of the arm 7 and the boom 6, components with the same name are components that correspond to each other.

[0077] Figures 9 and 10 are side and perspective views, respectively, showing the configuration of the arm 7 in the work machine shown in Figure 1. Figure 11 is a cross-sectional view corresponding to line XI-XI in Figure 9. Figure 12 is a cross-sectional view corresponding to line XII-XII in Figure 9.

[0078] As shown in Figures 9 and 10, the arm 7 has a box-shaped structure BX2, a bucket connecting boss 7a, a link connecting boss 7b, and a boom connecting boss 7c. The box-shaped structure BX2 has a first end 71 and a second end 72. The first end 71 faces the bucket 8 (Figure 1). The second end 72 faces the arm cylinder 11 (Figure 1).

[0079] The box-shaped structure BX2 is composed of multiple plate members. These plate members include an upper plate TP2, a pair of side plates SP3 and SP4, and a lower plate BP2. The pair of side plates SP3 and SP4 and the lower plate BP2 are joined at the second end 72. As shown in Figure 9, in a side view, the lower plate BP2 is bent in a convex shape downwards.

[0080] The bucket connecting boss 7a, the link connecting boss 7b, and the boom connecting boss 7c are each cast, for example, by casting. The bucket connecting boss 7a, the link connecting boss 7b, and the boom connecting boss 7c are also referred to as boss members. The bucket connecting boss 7a is the part into which the arm top pin 15 (Figure 1) is inserted. The bucket connecting boss 7a is joined to the first end 71, for example, by welding.

[0081] The link connecting boss 7b is the part into which the link pin 16 (Figure 1) is inserted. The link connecting boss 7b is provided so as to penetrate each of the pair of side plates SP3 and SP4. The link connecting boss 7b is located closer to the bucket connecting boss 7a than to the boom connecting boss 7c.

[0082] The boom connecting boss 7c is the part into which the boom top pin 14 (Figure 1) is inserted. The boom connecting boss 7c is provided so as to penetrate each of the pair of side plates SP3 and SP4. The boom connecting boss 7c is positioned near the bend of the lower plate BP2.

[0083] As shown in Figures 9 and 10, the box-shaped structure BX2 has upper corners 81 and 82. Each of the upper corners 81 and 82 corresponds to an example of a "corner" in this disclosure. Upper corner 81 is the upper left corner of the box-shaped structure BX2, and upper corner 82 is the upper right corner of the box-shaped structure BX2. At upper corner 81, the box-shaped structure BX2 has a first corner region 86 and a second corner region 87. At upper corner 82, the box-shaped structure BX2 has a third corner region 88 and a fourth corner region 89.

[0084] As shown in Figures 11 and 12, the box-shaped structure BX1 has an internal space IP2 surrounded by an upper plate TP2, a pair of side plates SP3 and SP4, and a lower plate BP2. Upper welded sections W5 and W6, formed by welding, are provided in the first corner region 86 and the third corner region 88, respectively.

[0085] The box-shaped structure BX2 has lower corners 83 and 84. Lower corner 83 is the lower left corner of the box-shaped structure BX2, and lower corner 84 is the lower right corner of the box-shaped structure BX2. Lower welded sections W7 and W8, formed by welding, are provided at each of the lower corners 83 and 84.

[0086] As shown in Figure 9, the upper plate TP2 has a flat portion FP2 and a curved portion RP2. The flat portion FP2 has a surface OF2 and a back surface IF2. The flat portion FP2 constitutes the first end E3 of the upper plate TP2. The curved portion RP2 constitutes the second end E4 of the upper plate TP2.

[0087] The upper plate TP2 has a first plate material 31 and a second plate material 32. The first plate material 31 faces the bucket cylinder 12 (Figure 1). The bucket cylinder 12 corresponds to an example of a "hydraulic cylinder" in this disclosure. In a side view, a virtual straight line 98 that overlaps the outer surface (surface OF2) of the first plate material 31 intersects the second corner region 87. The side plate SP3 has, for example, a third plate material 33 and a fourth plate material 34. Although not shown, similar to the side plate SP3, the side plate SP4 has, for example, a fifth plate material and a sixth plate material.

[0088] The portion of the side plates SP3 and SP4 located between the second corner region 87 and the fourth corner region 89 is referred to as the upper surface portion 30. A welding line WL2 is provided on the upper surface portion 30, for example. The welding line WL2 may join the side plates SP3 and SP4 to the backing plate P2.

[0089] As shown in Figure 9, the arm 7 includes a bucket cylinder bracket 7d and a second arm cylinder bracket 7e. The bucket cylinder bracket 7d corresponds to an example of a "cylinder bracket" in this disclosure.

[0090] The bucket cylinder bracket 7d is a part that rotatably supports one end of the bucket cylinder 12 (Figure 1). The bucket cylinder 12 is positioned to extend along the direction toward the first end 71 from the bucket cylinder bracket 7d. The bucket cylinder bracket 7d is joined to the upper plate TP2. The bucket cylinder bracket 7d protrudes upward from the upper plate TP2.

[0091] The second arm cylinder bracket 7e is the part that rotatably supports the other end of the arm cylinder 11 (Figure 1). The second arm cylinder bracket 7e is joined to the lower plate BP2. The second arm cylinder bracket 7e protrudes downward from the lower plate BP2.

[0092] The arm 7 has, for example, an internal rib 39. The lower end of the internal rib 39 is joined to the boom connecting boss 7c. The upper end of the internal rib 39 is joined to the upper plate TP2.

[0093] <Method of manufacturing the boom> Next, the method of manufacturing the boom 6 will be explained using Figures 13 to 15.

[0094] Figure 13 is a schematic flowchart illustrating a method for manufacturing a boom in one embodiment of the present disclosure. Figure 14 is a schematic diagram illustrating step S2 in which the side plate, bottom plate, and boss member are joined in the boom manufacturing method. Figure 15 is a schematic diagram illustrating step S2 in which the side plate, bottom plate, and boss member are joined, step S3 in which the internal ribs are joined, and step S4 in which the top plate is joined in the boom manufacturing method.

[0095] As shown in Figure 13, the method for manufacturing the boom 6 according to this embodiment mainly comprises the steps of: step S1 for preparing the parts; step S2 for joining the side plate, bottom plate, and boss member; step S3 for joining the internal ribs; step S4 for joining the top plate; step S5 for final joining; and step S6 for final hole processing.

[0096] Step S1 includes step S11, which involves bending the fourth plate material, and step S12, which involves joining the third plate material and the fourth plate material. In step S11, the second corner region 57 is formed by bending the fourth plate material 44 (one of the multiple plate materials that make up the box-shaped structure BX1). Next, in step S12, the third plate material 43 and the fourth plate material 44 are joined together, for example, by welding. This forms the side plate SP1. Note that step S11 may be performed after step S12 has been performed.

[0097] In step S1, the side plate SP2 is formed by the same process as in steps S11 and S12. The side plate SP2 is formed by joining the fifth plate material 45 and the sixth plate material 46 by welding. In addition, the upper plate TP1, lower plate BP1, center boss 6d, boom foot 6b, and boom top 6a are prepared.

[0098] As shown in Figure 14, in step S2, for example, the side plate SP2 is supported by a jig (not shown) (S2a in Figure 14). Specifically, the guide of the jig is placed over the hole into which the center boss 6d is inserted. Using the jig, the side plate SP2 and each of the boss members (center boss 6d, boom foot 6b, and boom top 6a) are aligned (S2b in Figure 14).

[0099] Next, the side plates SP1 are pressed against each of the boss members (S2c in Figure 14). Using a hydraulic jig (not shown), the lower plate BP1 is pressed upward against the side plates SP1 and SP2. With the lower plate BP1 pressed against the side plates SP1 and SP2, each component is tack-welded (S2d in Figure 14).

[0100] As shown in Figure 15, in step S2, the weld line WL1 is formed by butt welding of the side plates SP1 and SP2 (S2e in Figure 15). In the butt welding of the side plates SP1 and SP2, a backing plate P1 (Figure 5) is used as needed.

[0101] In step S3, the internal rib 49 is joined to the center boss 6d and the lower plate BP1 by welding (S3 in Figure 15). In step S3, welding is performed on parts of the box-shaped structure BX1 that require welding, such as welding the boom top 6a to the inner surfaces of the side plates SP1 and SP2.

[0102] In step S4, with the upper plate TP1 pressed downwards against the side plates SP1 and SP2, the upper plate TP1 is joined to the side plates SP1 and SP2 and the boom top 6a (S4a in Figure 15). In this way, the first corner region 56 is formed by joining two or more of the multiple plate materials (upper plate TP1 and side plate SP1) that make up the box-shaped structure BX1.

[0103] In step S4, the first arm cylinder bracket 6c is joined to the upper plate TP1 (S4b in Figure 15). Alternatively, the first arm cylinder bracket 6c may be joined to the upper plate TP1 in step S1.

[0104] In step S5, the main welding is performed using a welding robot. In step S6, the pilot holes provided in each of the boss members are enlarged. This adjusts the relative positional relationship between the through holes provided in each of the boss members. A pin (not shown) for rotatably supporting the boom cylinder 10 (Figure 1) is inserted into the through hole provided in the center boss 6d. Similarly, a boom foot pin 13 (Figure 1) and a boom top pin 14 (Figure 1) are inserted into the through holes provided in the boom foot 6b and boom top 6a, respectively. The boom 6 is thus manufactured.

[0105] In this embodiment, the first corner region 56 is formed by joining the upper plate TP1 and the side plate SP1. The second corner region 57 is formed by bending the fourth plate material 44 of the side plate SP1. Therefore, only a part of the upper corner 51 is formed by bending. Consequently, the accuracy of the bending process is improved compared to the case where the entire upper corner 51 is formed by bending. This suppresses the occurrence of defects such as misalignment of the welding position when the bent part is welded. As a result, productivity is improved.

[0106] According to this embodiment, the side plate SP1 is formed by joining the third plate material 43 and the fourth plate material 44 before the first corner region 56 is formed. Therefore, the third plate material 43 and the fourth plate material 44 can be joined even before the top plate TP1 is joined to the third plate material 43 and the fourth plate material 44. This makes it possible to perform double-sided welding, for example, in the butt welding of the third plate material 43 and the fourth plate material 44. Consequently, a backing plate is not required when joining the third plate material 43 and the fourth plate material 44. As a result, the reduction in the strength of the side plate SP1 caused by the use of a backing plate is suppressed.

[0107] <Modified Manufacturing Methods> Next, modified manufacturing methods for the boom 6 will be explained using Figures 16 and 17.

[0108] Figure 16 is a schematic flowchart showing a modified example of the method for manufacturing the boom 6. Figure 17 is a schematic diagram illustrating the process of forming the first box section and the second box section, and the process of joining the first box section and the second box section.

[0109] As shown in Figure 16, a modified version of the method for manufacturing the boom 6 mainly comprises the steps of forming a first box section S21, forming a second box section S22, joining the first box section and the second box section S23, final joining S24, and final hole machining S25.

[0110] Step S21 includes step S31, which involves joining a part of the side plate, the top plate, a part of the bottom plate, and a part of the boss member. As shown in S31 in Figure 17, in step S31, the third plate material 43, a part of the side plate SP2 (fifth plate material), the top plate TP1, a part of the bottom plate BP1 (seventh plate material 47), and a part of the boss member (boom top 6a) are joined by welding.

[0111] The third plate 43 and the upper plate TP1 are joined together to form a part of the first corner region 56 (Figure 3). As a result, the first box portion B1 is formed. The first box portion B1 is the part of the boom 6 that has at least a part of the first corner region 56 and the first end 61.

[0112] As shown in Figure 16, step S22 includes step S32 for bending the fourth plate material and step S33 for joining a part of the side plate, a part of the bottom plate, and a part of the boss member. Step S32 is the same as step S11 (Figure 13) described above.

[0113] As shown in S33 in Figure 17, in step S33, the fourth plate material 44, a part of the side plate SP2 (sixth plate material 46), a part of the bottom plate BP1 (eighth plate material 48), and a part of the boss member (center boss 6d and boom foot 6b) are joined by welding. This forms the second box section B2. The second box section B2 is the part of the boom 6 that has the second corner region 57 and the second end 62.

[0114] As shown in S23 in Figure 17, in step S23, the boom 6 is formed by joining the first box section B1 and the second box section B2 by welding. Therefore, the boom 6 is composed of the first box section B1 and the second box section B2.

[0115] Steps S24 and S25 are the same as steps S5 and S6 (Figure 13) described above, respectively. Although the above description explains a configuration in which step S22 is performed after step S21, steps S21 and S22 may be performed simultaneously, or step S22 may be performed before step S21.

[0116] Relatively long components of the boom 6, such as the side plates SP1 and SP2, can be difficult to store in containers, for example, on ships. Therefore, transporting these components is difficult. This embodiment includes a step S21 for forming the first box section, a step S22 for forming the second box section, and a step S23 for joining the first and second box sections. Compared to the side plates SP1 and SP2, the first box section B1 and the second box section B2 are each shorter. Therefore, the first box section B1 and the second box section B2 can be transported relatively easily. This allows, for example, the formation of the first box section B1 and the second box section B2, and the joining of the first and second box sections, to be carried out at different locations. As a result, the degree of freedom in the manufacturing of the boom 6 can be improved.

[0117] <Method of Manufacturing the Arm> Next, the method of manufacturing the arm 7 according to this embodiment will be described using Figures 18 and 19. The method of manufacturing the arm 7 is substantially the same as the method of manufacturing the boom 6 according to this embodiment (Figure 13) described above, except that the order in which the upper plate and lower plate are joined is different. The following description will focus on the differences from the method of manufacturing the boom 6 according to this embodiment.

[0118] Figure 18 is a schematic diagram illustrating the process of joining the side plate, top plate, and boss member, and the process of joining the internal rib, in the manufacturing method of the arm 7. Figure 19 is a schematic diagram illustrating the process of joining the bottom plate, in the manufacturing method of the arm 7.

[0119] As shown in Figure 18, in steps S2 and S3, welding is performed with the arm 7 inverted in the vertical direction Z from the state shown in Figure 9. In step S2, the upper plate TP2 is joined to the side plates SP3, SP4 and the bucket connecting boss 7a (S2 in Figure 18). In step S3, the internal rib 39 is joined to the boom connecting boss 7c and the upper plate TP2 (S3 in Figure 18).

[0120] As shown in Figure 19, in step S4, the lower plate BP2 is joined to the side plates SP3, SP4 and the bucket connecting boss 7a respectively (S4a in Figure 19). After the lower plate BP2 is joined, with the box-shaped structure BX2 inverted vertically, the bucket cylinder bracket 7d and the second arm cylinder bracket 7e are joined to the box-shaped structure BX2 respectively (S4b in Figure 19).

[0121] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than the foregoing description and is intended to include the meaning of equivalents of the claims and all modifications within the scope.

[0122] <Note> The embodiments described above include the following technical concepts. (Note 1) A component of a work machine comprising a box-shaped structure composed of a plurality of plate materials, wherein the box-shaped structure has a first corner region and a second corner region provided between the first corner region and the second end at a corner extending from a first end to a second end of the box-shaped structure, the first corner region is composed of a joint structure in which two or more of the plurality of plate materials are joined to each other, and the second corner region is composed of a bending structure in which one of the plurality of plate materials is bent. (Note 2) A component of a work machine according to Note 1, wherein the plurality of plate materials have an upper plate and side plates, the first corner region is composed of a joint structure in which the upper plate and the side plates are joined to each other, and the second corner region is composed of a bending structure in which the side plates are bent. (Note 3) The component of the work machine according to Note 2, further comprising a cylinder bracket to which a hydraulic cylinder is connected, wherein the cylinder bracket is joined to the upper plate, and the second corner region is provided between the cylinder bracket and the second end. (Note 4) The component of the work machine according to Note 3, wherein the upper plate has a first plate material that is flat and faces the hydraulic cylinder, and a second plate material that is connected to the first plate material and is located closer to the second end than the first plate material, the second corner region is joined to the second plate material, and in a side view, the second corner region intersects with a virtual straight line that overlaps the outer surface of the first plate material. (Note 5) The upper plate has a flat portion and a curved portion located closer to the second end than the flat portion; the flat portion has a surface that constitutes part of the outer surface of the box-shaped structure and a back surface opposite to the surface; the curved portion curves upward in the direction from the back surface toward the surface; and the second corner region is joined to the curved portion and extends along the thickness direction of the curved portion, a component of the work machine as described in any one of Notes 2 to 4.(Note 6) The side plate has a third plate that constitutes at least a part of the first corner region, and a fourth plate that is joined to the third plate and constitutes the second corner region, wherein the third plate is thinner than the fourth plate, a component of the work machine according to any one of Notes 2 to 5. (Note 7) The component of the work machine is a boom, a component of the work machine according to any one of Notes 1 to 6. (Note 8) The component of the work machine is an arm, a component of the work machine according to any one of Notes 1 to 6. (Note 9) A work machine comprising a work machine and a main body supporting the work machine, wherein the work machine has components of the work machine, the components of the work machine have a box-shaped structure made of a plurality of plate materials, the box-shaped structure has a first corner region and a second corner region provided between the first corner region and the second end at a corner extending from the first end to the second end of the box-shaped structure, the first corner region is made up of a joint structure in which two or more of the plurality of plate materials are joined to each other, and the second corner region is made up of a bending structure in which one of the plurality of plate materials is bent. (Note 10) The work machine according to Note 9, wherein the plurality of plate materials have an upper plate and side plates, the first corner region is made up of a joint structure in which the upper plate and the side plates are joined together, and the second corner region is made up of a bending structure in which the side plates are bent. (Note 11) The work machine according to Note 10, further comprising a cylinder bracket to which a hydraulic cylinder is connected, wherein the cylinder bracket is joined to the upper plate, and the second corner region is provided between the cylinder bracket and the second end. (Note 12) The work machine according to Note 11, wherein the upper plate has a first plate material that is flat and faces the hydraulic cylinder, and a second plate material that is connected to the first plate material and is located closer to the second end than the first plate material, wherein the second corner region is joined to the second plate material, and in a side view, the second corner region intersects with a virtual straight line that overlaps the outer surface of the first plate material.(Note 13) The upper plate has a flat portion and a curved portion located closer to the second end than the flat portion, the flat portion has a surface that constitutes part of the outer surface of the box-shaped structure and a back surface opposite to the surface, the curved portion curves upward in the direction from the back surface toward the surface, the second corner region is joined to the curved portion and extends along the thickness direction of the curved portion, the working machine according to any one of Notes 10 to 12. (Note 14) The side plate has a third plate material that constitutes at least part of the first corner region and a fourth plate material that is joined to the third plate material and constitutes the second corner region, the third plate material is thinner than the fourth plate material, the working machine according to any one of Notes 10 to 13. (Note 15) The working machine according to any one of Notes 10 to 13, the component of the working machine is a boom. (Note 16) The work machine described in any one of Notes 10 to 13, wherein the component of the work machine is an arm. (Note 17) A method for manufacturing a component of a work machine, wherein the component of the work machine has a box-shaped structure made of a plurality of plate materials, the box-shaped structure has a corner portion extending from a first end to a second end, the corner portion having a first corner region and a second corner region provided between the first corner region and the second end, and the method for manufacturing a component of a work machine comprises the steps of: forming at least a part of the first corner region by joining two or more plate materials from the plurality of plate materials; and forming the second corner region by bending one of the plurality of plate materials. (Note 18) The method for manufacturing components of a work machine as described in Note 17, wherein the plurality of plate materials have an upper plate and side plates, and in the step of forming at least a part of the first corner region, the upper plate and the side plates are joined together to form at least a part of the first corner region, and in the step of forming the second corner region, the side plates are bent to form the second corner region.(Note 19) The method for manufacturing a component of a work machine as described in Note 18, wherein the side plate is composed of a third plate material constituting the first corner region and a fourth plate material joined to the third plate material and constituting at least a part of the second corner region, and in the step of forming at least a part of the first corner region, the top plate and the third plate material are joined to form at least a part of the first corner region, in the step of forming the second corner region, the third plate material is bent to form the second corner region, and the method further comprises the step of joining the third plate material and the fourth plate material before the step of forming at least a part of the first corner region. (Note 20) The component of the work machine is composed of a first box portion having at least a part of the first corner region and the first end, and a second box portion having the second corner region and the second end, and the manufacturing method of the component of the work machine according to Note 18 comprises a step of forming the first box portion, which includes a step of forming at least a part of the first corner region, a step of forming the second box portion, which includes a step of forming the second corner region, and a step of joining the first box portion and the second box portion.

[0123] 1 Main body, 2 Working equipment, 3 Slewing body, 4 Cab, 4S Driver's seat, 5 Running body, 5Cr Tracks, 5M Travel motor, 6 Boom, 6a Boom top, 6b Boom foot, 6c First arm cylinder bracket, 6d Center boss, 7 Arm, 7a Bucket connecting boss, 7b Link connecting boss, 7c Boom connecting boss, 7d Bucket cylinder bracket, 7e Second arm cylinder bracket, 8 Bucket, 10 Boom cylinder, 11 Arm cylinder, 12 Bucket cylinder, 13 Boom foot pin, 14 Boom top pin, 15 Arm top pin, 16 Link pin, 17 Bucket link, 30, 40 Upper section, 31, 41 First plate, 32, 42 Second plate, 33, 43 Third plate, 34, 44 Fourth plate, 39, 49 Internal rib, 45 Fifth plate, 46 6th plate, 47 7th plate, 48 8th plate, 51, 52, 81, 82 Upper corner, 53, 54, 83, 84 Lower corner, 56, 86 1st corner area, 57, 87 2nd corner area, 58, 88 3rd corner area, 59, 89 4th corner area, 61, 71 1st end, 62, 72 2nd end, 98, 99 Virtual straight line, 100 Hydraulic excavator, B1 First box part, B2 Second box part, BP1, BP2 Lower plate, BX1, BX2 Box structure, E1, E3 First end, E2, E4 Second end, FP1, FP2 Flat plate part, IF1, IF2 Back side, IP1, IP2 Internal space, OF1, OF2 Surface, P1, P2 Backing plate, R Residual root part, RP1, RP2 Curved section, RX pivot axis, SP1, SP2, SP3, SP4 side plate, T arrow, TP1, TP2 top plate, W welded section, W1, W2, W5, W6 upper welded section, W3, W4, W7, W8 lower welded section, WL1, WL2 weld line, X front-back direction, Y left-right direction, Z up-down direction.

Claims

1. A component of a work machine comprising a box-shaped structure composed of multiple plate materials, wherein the box-shaped structure has a first corner region and a second corner region provided between the first corner region and the second end at a corner extending from a first end to a second end of the box-shaped structure, the first corner region is composed of a joint structure in which two or more of the multiple plate materials are joined together, and the second corner region is composed of a bending structure in which one of the multiple plate materials is bent.

2. The component of the work machine according to claim 1, wherein the plurality of plate materials have an upper plate and side plates, the first corner region is formed by a joint structure in which the upper plate and the side plates are joined, and the second corner region is formed by a bending structure in which the side plates are bent.

3. The component of the work machine according to claim 2, further comprising a cylinder bracket to which a hydraulic cylinder is connected, wherein the cylinder bracket is joined to the upper plate, and the second corner region is provided between the cylinder bracket and the second end.

4. The upper plate comprises a first plate material which is flat and faces the hydraulic cylinder, and a second plate material which is connected to the first plate material and is located closer to the second end than the first plate material, the second corner region is joined to the second plate material, and in a side view, the second corner region intersects with a virtual straight line which overlaps the outer surface of the first plate material, the component of the work machine according to claim 3.

5. The upper plate has a flat portion and a curved portion located closer to the second end than the flat portion; the flat portion has a surface that constitutes part of the outer surface of the box-shaped structure and a back surface opposite to the surface; the curved portion curves upward in the direction from the back surface toward the surface; and the second corner region is joined to the curved portion and extends along the thickness direction of the curved portion, a component of the work machine according to claim 2 or claim 3.

6. The side plate comprises a third plate material that constitutes at least a part of the first corner region, and a fourth plate material that is joined to the third plate material and constitutes the second corner region, wherein the third plate material is thinner than the fourth plate material, a component of the work machine according to claim 2 or claim 3.

7. The component of the work machine according to claim 1 or claim 2, wherein the component of the work machine is a boom.

8. The component of the work machine according to claim 1 or claim 2, wherein the component of the work machine is an arm.

9. A work machine comprising a work machine and a main body supporting the work machine, wherein the work machine has components, the components of the work machine have a box-shaped structure made of a plurality of plate materials, the box-shaped structure has a first corner region and a second corner region provided between the first corner region and the second end at a corner extending from a first end to a second end of the box-shaped structure, the first corner region is made up of a joint structure in which two or more of the plurality of plate materials are joined together, and the second corner region is made up of a bending structure in which one of the plurality of plate materials is bent.

10. The work machine according to claim 9, wherein the plurality of plate materials have a top plate and side plates, the first corner region is formed by a joint structure in which the top plate and the side plates are joined, and the second corner region is formed by a bending structure in which the side plates are folded.

11. The work machine according to claim 10, further comprising a cylinder bracket to which a hydraulic cylinder is connected, wherein the cylinder bracket is joined to the upper plate, and the second corner region is provided between the cylinder bracket and the second end.

12. The work machine according to claim 11, wherein the upper plate has a first plate material that is flat and faces the hydraulic cylinder, and a second plate material that is connected to the first plate material and is located closer to the second end than the first plate material, the second corner region is joined to the second plate material, and in a side view, the second corner region intersects with a virtual straight line that overlaps the outer surface of the first plate material.

13. The work machine according to claim 10 or 11, wherein the upper plate has a flat portion and a curved portion located closer to the second end than the flat portion, the flat portion has a surface that constitutes part of the outer surface of the box-shaped structure and a back surface opposite to the surface, the curved portion curves upward in the direction from the back surface toward the surface, and the second corner region is joined to the curved portion and extends along the thickness direction of the curved portion.

14. The work machine according to claim 10 or 11, wherein the side plate comprises a third plate material that constitutes at least a part of the first corner region, and a fourth plate material that is joined to the third plate material and constitutes the second corner region, and the third plate material is thinner than the fourth plate material.

15. The work machine according to claim 9 or claim 10, wherein the component of the work machine is a boom.

16. The work machine according to claim 9 or claim 10, wherein the component of the work machine is an arm.

17. A method for manufacturing a component of a work machine, wherein the component of the work machine has a box-shaped structure made of a plurality of plate materials, the box-shaped structure has a corner portion extending from a first end to a second end, the corner portion having a first corner region and a second corner region provided between the first corner region and the second end, and the method for manufacturing a component of a work machine comprises the steps of: forming at least a part of the first corner region by joining two or more plate materials from the plurality of plate materials; and forming the second corner region by bending one of the plurality of plate materials.

18. The method for manufacturing components of a work machine according to claim 17, wherein the plurality of plate materials each have a top plate and side plates, and in the step of forming at least a part of the first corner region, the top plate and the side plates are joined together to form at least a part of the first corner region, and in the step of forming the second corner region, the side plates are bent to form the second corner region.

19. The method for manufacturing a component of a work machine according to claim 18, wherein the side plate is composed of a third plate material constituting the first corner region and a fourth plate material joined to the third plate material and constituting at least a part of the second corner region, and in the step of forming at least a part of the first corner region, the top plate and the third plate material are joined to form at least a part of the first corner region, in the step of forming the second corner region, the third plate material is bent to form the second corner region, and the method further comprises the step of joining the third plate material and the fourth plate material before the step of forming at least a part of the first corner region.

20. The component of the work machine is composed of a first box portion having at least a part of the first corner region and the first end, and a second box portion having the second corner region and the second end, and the method for manufacturing the component of the work machine according to claim 18, comprising the steps of: forming the first box portion, which includes the step of forming at least a part of the first corner region; forming the second box portion, which includes the step of forming the second corner region; and joining the first box portion and the second box portion.

Images